The present invention relates to an improved structure for a probe which utilises transmission of signals, e.g. representing stylus triggering information for measuring physical dimensions.
Probes for dimensional measurement have been used without wires for transmitting signals representing coordinates to a fixed base station (e.g. on a machine tool).
Signals are known to be transmitted using infrared light, radio waves or inductively, and a number of transmitters and receivers for the signals are generally mounted on an external surface of the probe. One such probe is shown in European Patent No. 337669.
In hostile conditions these transmitters/receivers can become damaged. Additionally each needs to be sealed against ingress of foreign materials into the probe.
One such commercially available probe uses a window to cover and protect infrared transmitters/receivers. This window can be in the form of an annular ring covering a recessed row of transmitters/receivers. The transmitters/receivers need to be mounted to an external surface of the probe inside the window.
The present invention provides a measurement probe comprising a housing having a signal transmitter and/or receiver and a circuit board therein and comprising a window transparent to the signal, characterised in that the said transmitter and/or receiver is mounted to the circuit board, adjacent the window.
Preferably the window is in the form of an annulus.
Preferably the said transmitter and/or receiver is a plurality of infrared transmitter and receiver components which may be spaced within and around the annulus. The circuit board may be placed within the annular window and may be bent at lines of weakness. The window may be fully or partially transparent to the light and may include a filter and/or visually attractive coating.